Swimmers like runners have selected training schedules that may be determined by a coach. Long distance swims for endurance are scheduled for one day at a slow pace. A moderate distance at a moderate pace may be scheduled another day. A number of high speed swimming laps with a short break between laps may be scheduled for another training period. A timed fixed distance swim after a warmup may be scheduled on a following day. Different paces are selected for the training events. As a training program progresses, the paces will increase. There will be times however when the pace is decreased by a coach to provide rest and recovery time between training days. There may also be days when a swimmer will perform two of the above training events.
Pacing lights have been placed on the floor of swimming pools to provide a pace during training. Pools used by competitive swimmers have an end with shallow water and an end with deep water. On the shallow water end, a light for pacing is generally a few vertical feet below a swimmer's eyes when the swimmer's head is in the water. The line of sight is vertical when the swimmer's eyes are vertically above a pacing light. Distortion of light through the water and swimming goggles is small when the swimmer's head and face is in the water. Most of the time a place light will be either to the front or to the rear of the swimmer's eyes. Swimmers are trained to keep their heads in line with their bodies when under the water or partially below the water surface. Their range of view without moving their heads is limited by the swimming goggles. However, the range is still a substantial range.
A group of LEDs for pacing a swimmer may work well in the shallow end of a pool where the depth of the lights is substantially constant and the swimmer's eyes are in the water. As the LEDs descent into the deep end of the pool, the horizontal space between adjacent uniformly spaced lights decreases. The length, of a portion of a light strip descending into a deep end of a pool, increases to reach to a pool end. Changes in spacing between LEDs is increased to maintain a horizontal space between LEDs that is the same the entire length of the pool. The increased space between LEDs maintains the horizontal spacing and the selected pace.
An alternative pacing system holds the LEDs near the same depth from the shallow end to the deep end. A tension force on a rope of LEDs is required to hold the LEDs up above the pool floor in the deeper portion of the pool.